SUBFOSSIL REMAINS OF CHIRONOMIDAE FROM TWO SHALLOW LAKES REPRESENTING EXTREME ALTERNATIVE STATES

The remains of Chironomidae in the recent sediments of macrophyte-dominated Lake Rotcze and phytoplankton-dominated Lake Syczyñskie (Polesie Region) were analyzed in order to check their suitability for diagnosing the lake status according to the alternative equilibria concept and thus also the development of submerged vegetation. In both lakes chironomid capsules were predominated by phytophilous taxa but their relative abundance was higher in the phytoplankton-dominated lake. The percentage of pelophilous taxa in the lakes did not exceed 10%. The taxa richness of both phytophilous and pelophilous assemblages was higher in the macrophyte-dominated lake. Therefore I conclude that the presence of phytophilous forms, and even their prevailing contribution in the total chironomid numbers can not be sufficient to prove the existence of a macrophytic state of a lake. In order to put a proper diagnosis on the develop-ment of vegetation in the past, the detailed analyses of the qualitative and quantitative structure of both ecological as-semblages is needed. Key words: lakes, subfossil Chironomidae, macrophytes, alternative state